In many cleaning applications, it is desirable to remove contaminants (e.g., stains) from substrates, like metal, ceramic, polymeric, composite, glass and textile comprising substrates. Particularly, it is highly desirable to remove contaminants from clothing whereby such contaminants include dirt, salts, food stains, oils, greases and the like.
Typically, dry-cleaning systems use organic solvents, like chloro fluorocarbons, perchloroethylene and branched hydrocarbons to remove contaminants from substrates. In response to environmental concerns, other dry-cleaning systems have been developed that use inorganic solvents, such as densified carbon dioxide, to remove contaminants from substrates. The systems that use carbon dioxide to remove contaminants from substrates generally employ a surfactant and a polar co-solvent so that a reverse micelle may be formed to trap the contaminant targeted for removal.
In view of the environmental concerns associated with dry cleaning in, for example, halogenated hydrocarbons, many cleaning establishments have expressed their interests in cleaning with continuous phase solvents that comprise densified gases such as densified carbon dioxide as well as a biodegradable functionalized hydrocarbon or a silicon comprising surfactant. Unfortunately, however, cleaning with such solvents is not made easy because only very few surfactants are compatible with such continuous phases.
It is of increasing interest to develop surfactants that enhance cleaning in a system that uses a densified gas, functionalized biodegradable hydrocarbon and/or a silicon comprising solvent. This invention, therefore, is directed to a surfactant comprising a heterocyclic group that unexpectedly results in superior cleaning properties in a dry cleaning system that utilizes a densified gas, a functionalized biodegradable hydrocarbon and/or silicon comprising solvent.